The present invention relates to electronic/electric parts and an apparatus for processing substrates, which are used in a clean room.
As the high increasing of semiconductor device integration, adsorption of organic substances to a substrate, especially silicon wafer, is becoming an additional problem except particles adsorption (for example, xe2x80x9cCurrent Studies on Measurements of Gaseous Contaminants and their Removal Technologiesxe2x80x9d written by Fujii, Air Cleaning Vol. 32, No. 3, page 43 (1994), Japan Air Cleaning Academy).
According to the studies conducted by the authors of the present invention, even after the interior atmosphere of a clean room has been cleaned up at a high degree, various organic compounds such as aliphatic hydrocarbons, organic carboxylic esters, phenols or oxides thereof, and amines are detected from the surfaces of silicon wafers placed in the clean room. These organic compounds very much coincide with the additives added to resin base materials. Therefore, the inventors suspect that the source of generating these compounds may be electronic/electric parts such as electric cord coating and print wiring substrate.
Additives are used to impart various functions to the resin products, and they contain organic compounds of relatively low molecular weights. Therefore, these compounds tend to volatilize from the resin base material while in use. More specifically, aliphatic hydrocarbons are generated from a lubricant added to improve the extrusion ability, and organic carboxylic esters are generated from a plasticizer added to maintain the physical property. Further, phenols and oxides thereof are generated from an anti-oxidizing agent added to prevent the deterioration due to oxidization during the forming process or thereafter, and amines stem from an anti-electrostatic agent added to prevent the electrostatic charge-up. When these organic substances adhere to the surface of a silicon wafer, a problem such as the deterioration of the film quality of the gate oxide layer arises, resulting in the low production yield.
In the manufacturing step for the highly integrated semiconductor device, the internal atmosphere of the clean room is cleaned with use of a chemical filter. However, the adsorption of organic substances onto the surface of the substrate is not sufficiently prevented. Under these circumstances, there has been a demand, on the part of customers, for a technology capable of effectively preventing the adsorption of organic substances onto the surface of the substrate.
The object of this invention is to provide an electronic/electric part and a substrate processing apparatus, in which the amount of release (volatilization) of organic substances is suppressed or reduced while being used in a clean room.
The inventors of the present invention studied the components of the additives contained in the resin base materials that constitute electronic/electric parts for use in a clean room, as well as their molecular weights. They found some components that were not released as out-gases from the resin base material at the temperature at which they were used, and also the range of molecular weight of these components, thus achieving the present invention.
More specifically, the inventors found that when the molecular weight of an organic substance used as a component of an additive becomes larger, the volatility (the property that an organic substance is released as out-gas from the resin base material) becomes lower. At the same time, as the molecular weight becomes larger, the adsorbing ability to the surface of a substrate (the property of the substrate surface adsorbed with an organic substance physically or chemically) becomes larger in some cases. As a result, the amount of organic substances adsorbed to the silicon wafer increases as the molecular weight increases in the case where the molecular weight of the organic substance is small, and reaches the maximum value at a certain molecular weight. The present invention has been achieved on the basis of such a finding.
The present invention provides electronic/electric parts containing a resin base material and additives to be used in a clean room in which the atmosphere is controlled to process a substrate in semiconductor device industries. The electronic/electric parts are characterized in that the additives contain one or more materials selected from the group consisting of an anti-electrostatic agent of a organic nitrogen-containing nonionic compound having a molecular weight of 350 or higher, an anti-oxidizing agent of a phenol compound having a molecular weight of 300 or higher, a lubricant, a plasticizer, a fire retardant, and a water repellent, and that the additives do not easily release gaseous organic substances from the resin base material under a condition where the part is used.
The present invention further provides a substrate processing apparatus which is to be installed in a clean room wherein the atmosphere is controlled to process a substrate to manufacture a semiconductor device and which comprises an electronic/electric part used for supplying electricity or transmitting or receiving a signal. The apparatus is characterized in that the electronic/electric part contains a resin base material and additives added to the resin base material. It is also characterized in that the additives contain one or more materials selected from the group consisting of an anti-electrostatic agent of a nitrogen-containing nonionic compound having a molecular weight of 350 or higher, an anti-oxidizing agent of a phenolic compound having a molecular weight of 300 or higher, a lubricant, a plasticizer, a fire retardant, and a water repellent. Further, the additives hardly release gaseous organic substances from the resin base material under a condition where the part is used.